1 files changed, 29 insertions, 0 deletions
diff --git a/tests/ui/lint/issue-1866.rs b/tests/ui/lint/issue-1866.rs
new file mode 100644
index 00000000000..caac0c50414
--- /dev/null
+++ b/tests/ui/lint/issue-1866.rs
@@ -0,0 +1,29 @@
+// build-pass
+#![allow(dead_code)]
+#![allow(non_camel_case_types)]
+#![warn(clashing_extern_declarations)]
+
+// pretty-expanded FIXME #23616
+
+mod a {
+    pub type rust_task = usize;
+    pub mod rustrt {
+        use super::rust_task;
+        extern "C" {
+            pub fn rust_task_is_unwinding(rt: *const rust_task) -> bool;
+        }
+    }
+}
+
+mod b {
+    pub type rust_task = bool;
+    pub mod rustrt {
+        use super::rust_task;
+        extern "C" {
+            pub fn rust_task_is_unwinding(rt: *const rust_task) -> bool;
+        //~^ WARN `rust_task_is_unwinding` redeclared with a different signature
+        }
+    }
+}
+
+pub fn main() {}